1. Field of the Invention
The present invention relates to ophthalmic surgical procedures for the correction of refractive defect. More particularly, the present invention relates to an ophthalmic refractive correction procedure known as LASIK, wherein a corneal flap is produced thereduring. Still more particularly, the present invention relates to an ophthalmic instrument and method which prepares an eye for LASIK flap procedure to thereby provide minimization of post operative complications of the LASIK flap procedure.
2. Description of the Prior Art
Surgery to correct refractive defect of the eye have been practiced in the ophthalmic arts for a number of years. One currently well known and highly regarded such procedure is known as LASIK. LASIK stands for "laser in situ keratomileusis".
An over view of LASIK involves the following steps: cutting a flap of corneal tissue in front of the pupil, folding the flap out of the way of the underlying cut corneal interface, laser oblating the underlying corneal interface to the patient's refractive prescription, then folding the flap back, whereupon naturally occurring eye suction retains the flap in place.
In order to cut the flap, LASIK involves a device known as a "microkeratome". The microkeratome is placed upon the eye and has an interface which when pressed upon the eye causes flattening of the cornea. The microkeratome has a sliding blade mechanism whereby a surgical blade is slid across the eye to produce the flap. The microkeratome provides for the blade to stop short of severing the flap from the cornea, the connection being referred to as the "hinge". It is the hinge which allows the flap to be safely folded or rolled out of the way for the refractive oblation procedure, and then folded or rolled back without alignment error.
The flap cutting process is quite sensitive to the satisfactory outcome of LASIK. In this regard, the microkeratome flattens the eye prior to the flap cut in order that a uniform thickness flap is produced. The flap cut involves cutting through an outer and inner layer of the cornea to a preset depth. The corneal outer layer is called the "epithelium" and the corneal inner layer is called the "stroma". The epthelium is under 50 microns thick and the flap thickness is about 160 to 180 microns. Accordingly, the flap cutting procedure provides a circular shaped stroma interface between the flap and the remainder of the cornea, and a ring shaped epithelium interface between the periphery of the flap and the remainder of the cornea.
One of the most feared complications of LASIK is that during the flap cutting procedure, some epithelium cells can attach to the blade and become deposited at the stromal interface. Should this occur, when the flap is repositioned these epithelium cells will remain located at the stroma interface. These errant epthelium cells can then develop into inclusion cysts, leading to a variety of adverse symptomatology.
Accordingly, what is needed in the art is prevention of epithelium cells from being deposited at the stroma interface during LASIK.